at what stage RBC lacks a nucleus?

Production of New RBC's - Erythropoiesis (takes 4 days)

1. Hemocytoblasts - Stem cells in the bone marrow from which all blood cells form.

2. Proerythroblasts - are produced by the division and differentiation of stem cells.

3. Basophilic (early) erythroblasts - During this stage in erythropoiesis hemoglobin synthesis begins.

4. Intermediate erythroblasts - At this time, we see the accumulation of hemoglobin due to its continued synthesis.

5. Late erythroblasts - During this stage the nucleus is extruded from the cell.*********** --HERE!

6. Reticulocyte - These cells exhibit a net-like appearance or reticulum in their cytoplasm when stained. A small number of reticulocytes (only 1 to 3% of the circulating red cells) are found in the circulation.

7. Mature erythrocytes - At this final stage of maturation there is a loss of ribosomes. These cells enter the circulation.